[all-commits] [llvm/llvm-project] ce1270: [RISCV] Remove shadow register list passed to Allo...

[Craig Topper via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: ce1270fc7e3d71f5769d4f9d151b275c6733c89d
      https://github.com/llvm/llvm-project/commit/ce1270fc7e3d71f5769d4f9d151b275c6733c89d
  Author: Craig Topper <craig.topper at sifive.com>
  Date:   2020-11-05 (Thu, 05 Nov 2020)

  Changed paths:
    M llvm/lib/Target/RISCV/RISCVISelLowering.cpp

  Log Message:
  -----------
  [RISCV] Remove shadow register list passed to AllocateReg when allocating FP registers for calling convention

The _F and _D registers are already sub/super registers. When one gets allocated all its aliases are already marked as allocated. We don't need to explicitly shadow it too.

I believe shadow is for calling conventions like 64-bit Windows on X86 where have rules like this

CCIfType<[i32], CCAssignToRegWithShadow<[ECX , EDX , R8D , R9D ],
                                         [XMM0, XMM1, XMM2, XMM3]>>

For that calling convention the argument number determines which register is used regardless of how many scalars or vectors came before it.

Removing this removes a question I had in D90738.

Differential Revision: https://reviews.llvm.org/D90801